Born in poverty, he was trained in religion by pious parents. For many years he embraced poverty as God’s will for him, and spent his time caring for the poor and sick. When he worked the fields, an angel would sometimes man the plow so that Guy could pray without distraction. He hung around the local church so much the priest made him the parishsacristan; Guy then lived in the church, and often spent all night in prayer.

A merchant from Brussels, Belgium either decided to give the boy a leg up in the world, or figured that Guy was a bumpkin who could be defrauded; versions vary. Either way, he offered Guy a part share in a new project that could make him rich. In the first ocean-going expedition in the project, the ship involved sank; Guy took it as a sign that he was right to begin with, and returned to his old life of poverty.

Many post-mortem miracles attributed to him. An annual festival grew up in the area around his grave, with most of the activities involving horses and the people who work with them because his grave, which was lost for years, was uncovered by a horse.